1. Field of the Invention
This invention relates to a well packer for forming a fluid barrier between the interior of a casing string and the exterior of a pair of tubing strings. 2. Description of Related Art
It is common practice in the oil and gas industry to use well packers in the bore of a well around the well tubing to seal the annulus between the well tubing and the well bore wall for isolating one or more vertical portions of the well bore. The well bore wall is usually defined by a casing string. Well packers are used in testing, treating and producing wells and in disposal well applications. These various and diverse systems employing well packers involve a wide range of depths at which the packers are used, environments which may produce extremes of high temperature and pressure as well as corrosive fluids, brine solutions, water, steam and other natural formation fluids and fluids used in treating and producing wells. The high cost of running, setting and pulling packers in wells which require handling equipment at the surface as well as substantial periods of shut-down time makes it highly desirable to use packers capable of relatively simple set and release within the well bore. It is particularly desirable for such a packer to be simple in construction with a minimum number of parts.
Well packers for directing fluid flow through a pair of tubing strings have been used for many years. Examples of prior dual string well packers are shown in U.S. Pat. No. 3,094,168 to W. D. Myers; U.S. Pat. No. 3,167,127 to P. S. Sizer; U.S. Pat. No. 3,326,292 to C. R. Young et al; and U.S. Pat. No. 3,336,983 to J. F. De Rochemont. These patents disclose various methods for completing wells with dual tubing strings and various methods for installing and releasing a dual well packer. U.S. Pat. No. 3,198,254 to E. H. Wise et al and U.S. Pat. No. 3,335,800 to W. D. Myers are particularly relevant to the present application because both patents disclose a dual string well packer which is set and released by longitudinal movement of the tubing strings relative to each other. The above listed patents are incorporated by reference for all purposes within this application.